4 wheel drive not working

I would start by removing and disassemblying the hubs. They get dirty and the grease dries out and things stick. Start with that. Also, if you hear the clicking in 2wd, check the CV joints.

If one of the front axles does not lock to the wheel--Even in 4X4, all power to the front is transferred to the least resistance. Thus freewheeling the "loose" axle fruitlessly inside the unlocked wheel (unless your front diff. Is positive traction--you will then be in 3 wheel drive!) Remove and clean the hubs, you might get over, on Ole Murphy! The Medic

Sounds like you have a prblem with the motor for the transfer case. Probalyl going bad or is bad. Should start there hope it helps let me know pat

OK sorry I did respond but you must of not recieved it for some reason anyway here is the next step. This test is done on the 5 pin harness at the module. You will unplug the 5 pin harnes and follow the instructions below and there is a pic of what pin is what ok. After the test let me know what you find so we can go to the next step.
1) connect ohm meter between term 1 and 2 and then press and hold the 4x4 switch and you should get 50 ohms.
2) connect ohm meter between term 1 and 3 and press the low range switch and you should get 50 ohms.
3) Now make a jumper wire that you can use to put between term 4 and a good ground, turn the key on engine off and the 4x4 in the instrument cluster and the low range 4x4 bar should light up. Turn key off and remove jumper wire.
4) Now connect the jumper wire between term 5 and ground and turn key on engine off the 4x4 in the instrument panel and the 4x4 bar should light up. Let me know what you find and and we will go to the next step after this.

Don't know if it will cost alot yet haven't found the problem yet. I do replace the 4x4 shift motors alot the one on the transfer case and they run about 150 anyway lets test the 8 pin connector at the motor I will walk you through the steps and include a pic so you know what pin is what ok.
1) key off connect your ohm meter between term 1 and ground (with automatic trans put in neutral) should read less then 50 ohm's.
2)Now connect you ohm meter between term 2 and 3 it should read between 200 to 350 ohms. Now repeat this step between terms 8 and then term 4 then 8 and 5 then 8 and 6 then 8 and 9 resistance should be between 200 and 350 ohms at each step. If not then the speed sensor needs to be replaced. Here is the pic for this test.

Now it this pans out then here is a test on the the other 8 pin connector at the module.
1) Key off connect your volt meter between 8 and gound you should see battery voltage.
2)Now connect meter between term 7 and gound and turn key on should see battery voltage. Turn key off.
3) Set back to ohms and connect between term 6 and ground should be less then 10 volts. Now connect between term 4 and 5 should also be less then 10 ohms.
4)Connect between 3 and ground then between 2 and ground both should read 0 ohm.

Ok if you have done all the steps above and all checked out as it should then the 4x4 shift motor on the back of the transfer case needs to be replaced. Let me know if something did test right. It is very important that you do all the steps as discribed. Thanks and let me know how it goes.

Now there is no vacuum for this version of the 4x4 system. In 95 they started that. Now if you want we can walk through some tests but it will start with ohming the speed sensor (the one on the top of the rear differetial) then it will move to the module tests as these are the common problem for this system. Get back to me with what you would like to do.

Ok let have the truck do a self test on the system. You need to locate the 4x4 module it is located to the left of the speaker on the right side in the instrument panel. Once you found it you need to unplug the 5 pin and 8 pin connector from the module. Now turn the key on engine off does the 4x4 light flash or is one steady. Let me know what you find and we will take it from there.